Scanning-as-Normal-User-on-Wierd-Scanner-Mini-HOWTO
---------------------------------------------------

Till Kamppeter

Original version I presented on MandrakeClub:
http://www.mandrakeclub.com/modules.php?op=modload&name=Splatt_Forum&file=viewtopic&topic=5895&forum=13

This version can also be used with non-Mandrake distros.

The problem is that the SANE driver for some scanners access the
parallel port (or any other port or proprietary card) directly,
without use of the kernel. Such way of device access is only possible
for root. Due to the kernel not being used there is no special file in
/dev or /proc which represents scanner and whose permissions can be
opened for normal users.

1. Make sure that saned is installed as in some distros it can be in
   an extra package (for example in Mandrake, type "urpmi saned" as
   root or use rpmdrake there).

2. Get root and stay root for the next steps. Create or edit
   /etc/xinetd.d/saned (we assume xinetd is used as in most modern
   distros):

      # default: off
      # description: The sane server accepts requests \
      # for network access to a local scanner via the \
      # network.
      service sane
      {
              disable = no
              port            = 6566
              socket_type     = stream
              wait            = no
              groups          = yes
              user            = root
              group           = root
              server          = /usr/sbin/saned
      }

   It can be already provided by your distro, but probably with

      user = saned
      group = saned

   Make sure that you have

      user = root
      group = root

   Add the line

      sane 6566/tcp # SANE Control Port

   to /etc/services if your distro didn´t put it there already.

3. Restart xinetd with

      service xinetd restart

4. Add a line only containing "localhost" in both
   /etc/sane.d/saned.conf and /etc/sane.d/net.conf. Make sure that in
   /etc/sane.d/dll.conf is a line containing only "net" and a line
   containing only the name of the driver for your scanner, both
   without comment sign ("#") in the beginning. Make also sure that
   the configuration file for your scanner driver /etc/sane.d/<your
   scanner´s driver>.conf is correctly set up (see "man sane-<your
   scanner´s driver>").

   Mandrake Linux users can also proceed as follows:

   Start Scannerdrake

      scannerdrake

   and click on "Scanner sharing". Mark "The scanners on this machine
   are available to other computers" and "Use scanners on remote
   computers". Click on "Scanner sharing to hosts" and in the next
   window on "Add host". Then choose "Name/IP address of host:" and
   type "localhost" in the input line. Click "OK" and "Done". Now
   click "Use scanners on hosts: ..." and in the dialog appearing "Add
   host". In the next window choose "This machine" and click
   "OK". Click "Done" to get back into the "Scanner sharing" and "OK"
   to get back into the main window of Scannerdrake. Now you can close
   Scannerdrake.

5. Run X-Sane (or your preferred frontend) as normal user and you
   should be able to scan. Please report here whether it really works.

6. You can still share your scanner on a network, simply add the
   addresses of the clients to your /etc/sane.d/saned.conf file.

How does this work?

We use the network scanning facility of SANE, but our "network"
consists of only one machine, the machine where your parallel scanner
is connected to. You do not need a network card for it. Linux has a
virtual network consisting of only the local machine which is used
when your machine is called with the name "localhost" or the IP
address 127.0.0.1. So the server and the client are on the same
machine. The server is the "saned" which you have installed in step
(1). It calls the scanner driver and communicates with the scanner. To
make this possible you let it run with root privileges. This you have
configured in step (2) and (3). In step (4) you have told that the
local machine and no other machine can access to your scanner
(/etc/sane.d/saned.conf or scannerdrake's "Scanner sharing to hosts:"
button) and that locally started scanning software should search for
scanner servers on the local machine (/etc/sane.d/net.conf or
scannerdrake's "Use the scanners on hosts:" button). The client is the
X-Sane running as a normal user, started in step (5). It searches for
local scanners where a normal user has access to and for remote
scanners. In your case it searches only on the local machine and finds
the saned providing your scanner. This way the scanner driver runs as
root, but the scanning frontend, X-Sane, as normal user.


Troubleshooting:

Does your scanner work if you scan as root? If so, please check
whether running the command "ifconfig" lists the "lo" device and
whether your /etc/hosts file contains a line like

   127.0.0.1 localhost

If not, do "ifup lo" and then try to scan as user with my method
described above again.

If you have a personal firewall installed, go to the firewall config
tool of your distro (Mandrake: in the MCC ("Security" section), click
on "Advanced" and in the appearing input line enter/add the port) and
open the port 6566 (TCP if TCP/UDP has to be supplied).

Check whether /etc/services contains the line

   sane 6566/tcp # SANE Control Port

and add it if it is missing. Then enter the command

   service xinetd restart

and try to scan as user again. If it does not work, post the output of
the command shown on the SANE mailing list and also the config files
mentioned in this Mini-HOWTO.